In general, a device based on specifications of a universal serial bus (USB) (hereinafter, referred to as a USB device) is provided with an identifier such as a vendor ID (VID) and a product ID (PID).
When the USB device is connected to an information processor such as a personal computer (PC), the VID and the PID can be transmitted from the USB device side to the information processor side. Thereby, the information processor side can recognize which function the connected USB device has, as disclosed in JP-A-2005-184360.
Therefore, the information processor can read into memory a program of a device driver necessary for controlling the USB device on the basis of the VID or the PID transmitted from the USB device, thereby allowing the device driver to function. Furthermore, when a single device driver corresponds to a plurality of models different in function and performance, the USB device is identified for function and performance on the basis of the PID. Thus, an appropriate control according to the identified function and performance can be realized.